Zi Yu

Abstract: In the framework of the relativistic mean field theory including the hyperon-hyperon (YY) interactions, protoneutron stars with a weakly interacting light U boson are studied. The U-boson leads to the increase of the star maximum mass. The modification to the maximum mass by the U-boson with the strong YY interaction is larger than that with the weak YY interaction. The maximum mass of the protoneutron star is less sensitive to the U-boson than that of the neutron star. The inclusion of the U-boson narrows down the mass window for the hyperonized protoneutron stars. As g2/μ2 increases, the species of hyperons, which can appear in a stable protoneutron star decrease. The rotation frequency, the red shift, the momentum of inertia and the total neutrino fraction of PSR J1903-0327 are sensitive to the U-boson and change with g2/μ2 in an approximate linear trend. The possible way to constrain the coupling constants of the U-boson is discussed.

TL;DR: In this article, the relativistic energy losses of the direct Urca processes with nucleons and hyperons were studied in the degenerate baryon matter of neutron stars, and it was shown that the existence of hyperons decreases the abundance of protons and leptons, and can sharply suppress the neutrino emissivity of the N-DURCA processes.

Abstract: A detailed description of the baryon direct Urca processes A: n→p+e+ν¯e , B: Λ→p+e+ν¯e and C: Ξ−→Λ+e+ν¯e related to the neutron star cooling is given in the relativistic mean field approximation. The contributions of the reactions B and C on the neutrino luminosity are calculated by means of the relativistic expressions of the neutrino energy losses. Our results show that the total neutrino luminosities of the reactions A, B and C within the mass range (1.603–2.067) M⊙ ((1.515–1.840) M⊙ for TM1 model) for GM1 model are larger than the corresponding values for neutron star without hyperons. Furthermore, although the neutrino emissivity of the reaction A is suppressed with the appearance of the proton 1S0 superfluid, the contribution of the reactions B and C can still quicken a massive neutron star cooling. In particular, the reaction C in PSR J1614-2230 and J0348+0432 is not suppressed by the proton 1S0 superfluid due to the higher threshold density of the reaction C, which will further speed up the two pulsars cooling.

TL;DR: In this paper, it was shown that PSR J1614-2230 with mass of 1.97 ± 0.04M may include hyperons when the weakly interacting light boson (WILB) is considered.